Sorry if I'm misunderstanding the question, but it looks like the artist modeled those treads in the hipoly and baked them into the normal map.
If you're using Substance Painter, you can then use the AO/curvature maps and generators to mask off the raised parts of the treads to get the look of accumulated dust.
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If you're using Substance Painter, you can then use the AO/curvature maps and generators to mask off the raised parts of the treads to get the look of accumulated dust.
Hope that helps!